摘要:

Cross pollination of annual with perennial Avena species did not result in the production of hybrid seeds, but certain specific combinations produced ovary stimulation.

ISSN:1923-4287    

DOI:10.1139/cjr39c-004

出版商:NRC Research Press    

年代:1939

数据来源: NRC

摘要:

A new member of the Plasmodiophorales with rather unusual characteristics has been found parasitizing the roots of wheat grown in soil from three different localities in Ontario. In addition to spore clusters of theLignieratype, large, septate zoosporangia with conspicuous tubes for zoospore discharge are present. These multinucleate zoosporangia are produced by progressive lobular outgrowths from uninucleate amoebae and from the beginning are always surrounded by a thin wall. In the formation of resting spores, naked multinucleate myxamoebae develop first, then segment to form spore clusters without formation of a soral membrane. Both zoosporangia and resting spores produce identical zoospores with two flagella of unequal length.The somatic nuclear divisions in the growing myxamoebae are characterized by the simultaneous division of both the nucleolus and chromatin within a persistent nuclear membrane. During the transitional phase which follows, the nucleolus disappears and at the same time there is an intensification of the staining properties of the surrounding cytoplasm. Prior to segmentation of the myxamoebae to form the spore clusters, and in all divisions during growth of the zoosporangia, the nucleoli and nuclear membranes disappear, and divisions are of ordinary mitotic type.Relationship with the Plasmodiophorales is indicated by the form of the resting spore clusters, the method of nuclear division during growth of the myxamoebae, and the characteristic flagellation of the zoospore. Since the zoosporangial characteristics of this fungus differ from those of other genera within this order, it is considered desirable to place it in a new genus for which the binomialPolymyxa graminisis proposed.

ISSN:1923-4287    

DOI:10.1139/cjr39c-005

出版商:NRC Research Press    

年代:1939

数据来源: NRC

摘要:

Salicylic aldehyde, when added to soil at the rate of 50 p.p.m., seems to predispose wheat roots to attack by parasitic strains ofPythium arrhenomanes.Actinomyces erythropolisand a species ofPenicilliumhave been found in soil from the healthy area of a field partially infected with Browning root rot. These organisms caused the disappearance of salicylic aldehyde in an artificial medium.It is suggested that lack of activity on the part of such organisms in certain areas of a field may lead to an accumulation of salicylic aldehyde or products acting in a similar manner, and that this may be a predisposing factor in the appearance of Browning root rot caused byPythium arrhenomanes.

ISSN:1923-4287    

DOI:10.1139/cjr39c-006

出版商:NRC Research Press    

年代:1939

数据来源: NRC